The present invention describes a process for tracing documents in an interlocking computer system, and in particular a proxy-server interlocking system.
Modern Internet browsers enable one to introduce a proxy-server when requesting documents from the Internet. Normally the proxy-servers are equipped with a cache, so that documents frequently requested do not have to be fetched from the Internet freshly on each occasion. For major server providers or businesses this means an enormous saving of band width when connected to the Internet.
The caches can be linked with each other in the following ways:
Parent-relation: There are several small caches and a large central cache. If a proxy-server does not have a document requested in its own cache, it turns to its parent proxy-server, which fetches the document from its own cache or from the Internet.
Sibling-relation: If a proxy does not have a certain document in its cache, it interrogates one or more siblings, to see if they have this document already in their cache. If the answer is positive, it collects the document from the relevant sibling but otherwise from the Internet.
These two processes are very suitable if the parent-cache-proxy is not overloaded or if the number of siblings remains reasonable. It is not in practice reasonable, for example, to ask 20 siblings for a certain document. Also, the individual parent cache will be overloaded if it has to deal with queries from 20 powerful proxy-servers.
Another way of solving the problem of tracing documents is provided by the CARP protocol from Microsoft. This protocol is installed on every proxy-server and makes it possible to trace the documents stored on the proxy-servers. In this case the query from the user is routed via a hash function to an appropriate proxy-server, where the document is also stored. One disadvantage of this process is that if the documents are not in the interlinked proxy-server system, a second server is involved unnecessarily. The documents requested always have to be transferred from this server to the server interrogated by the user.
Consequently, it is the task of the present invention to provide a process and system making it possible to rapidly and simply trace documents stored in an interlocked computer system. This task is covered by the characteristics of claims 1, 14 and 15. Other preferred versions of the present invention are described in the sub-claims.